Why punish someone just for throwing a drink on a manager?

I am acook at a restaurant. Now I'm having to do dishes and cook both all because the dish girl got pissed a threw a drink on a manager. They didn't fire her but she can't work with the same manager around. I wish they could just mediate and shit and get her back to work so I can just focus on cooking and never have to do dishes again.
Why punish someone just for throwing a drink on a manager?
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